Public Domain (Score 1)

In the Public Domain aren't there to be no expectations of privacy. I know this was used by the defense in some nude shots of girls on the street in mardi gras for something like Girls Gone Wild, when they were being sued by the girl (I might be wrong on the particulars but it was something of the sort.) So, considering it was outside in the public domain why should the cops be any different. When in public expect to be watched/listened to. I thought wiretapping came into effect when privacy was expected i.e. inside ones own house.